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seen Jun 27 at 7:01

Oct
6
revised Name of property describing the number of times a function changes concavity?
formatting
Oct
6
comment HAKMEM 123: Fourier Clocks
In fact it doesn't, at least not for general sequences of curves. For instance, a sequence of curves that wrap $n^2$ times around concentric circles of radius $1/n$ has the constant curve at the centre as its limit, but the arc lengths diverge.
Oct
6
comment HAKMEM 123: Fourier Clocks
Rigorously speaking, how does the arc length of the partial sums going to infinity imply that the limit curve isn't rectifiable?
Oct
6
revised HAKMEM 123: Fourier Clocks
corrected sum
Oct
6
answered Questions about cracking playfair using a 'shotgun climbing hill' method
Oct
5
revised What's the distance between a ray and a sphere?
slight addendum
Oct
5
answered What's the distance between a ray and a sphere?
Oct
5
comment How to obtain a possible state space representation of this 2nd order transfer function?
I've cancelled my downvote since the question now provides context. I'm not sure how to interpret your comment "joriki thinks that it is a question without context [...] I can't add more information than that", which you apparently made after adding the additional information, i.e. when the question was no longer in the form I'd originally criticized.
Oct
5
comment How to obtain a possible state space representation of this 2nd order transfer function?
@madmax: I disagree. I'm probably not the only one here who knows little about control theory but enough about transfer functions and differential equations to perhaps be able to help if you formulate the question in a form accessible to a wider audience.
Oct
5
comment How to obtain a possible state space representation of this 2nd order transfer function?
I'm downvoting this question because after having been made aware at this question of the need for context, you are again posting a question without context. What are $s$, $x$, $u$ and $y$?
Oct
5
comment Voronoi region as a polyhedron
@Fernandez: OK; in that case, you're done. I've edited my answer in response to your comment and edit.
Oct
5
revised Voronoi region as a polyhedron
adapted to modified question and comment
Oct
5
comment Voronoi region as a polyhedron
I didn't mean to substitute it by the visually obvious fact; I meant that the argument is quite a bit more complicated than the direct transformation I sketched in my answer.
Oct
5
comment Voronoi region as a polyhedron
That's rather a roundabout way of doing it :-)
Oct
5
answered Voronoi region as a polyhedron
Oct
5
comment Some question of affine algebraic set
You haven't accepted any of the answers to your previous questions -- have none of them been acceptable?
Oct
4
comment computing angles from combined rotation matrixes
@Alfio: No, your problems don't all come from the fact that Euler angles are not unique. The angles reflected at $\pi/2$ describe the wrong rotation; they're not equivalent to the correct angles. Equivalent angles would all yield the same rotation when you plug them into build3Drot; whereas these angles would lead to the wrong sign on the cosine. Yes, resorting to quaternions would help you get rid of this problem. Yes, you could then get correct Euler (not "euleur") angles from the quaternions (if you still need them). No, you couldn't get unique Euler angles, since there's no such thing.
Oct
4
awarded  Epic
Oct
4
comment Parametric equation for a plane perpendicular to a vector
None of the three answers given so far is an improvement over what you'd already got (and I don't think there can be any). In each answer, there's a case distinction according to which of $a,b,c$ is non-zero; you can do the same in the solution you already had. (craftsman.don's answer hides the case distinction in "given a normal vector $N$", which also requires a case distinction because no normal vector will work for all cases.)
Oct
4
comment Prove the definitions of $e$ to be equivalent
Don't you need to argue with uniform convergence to interchange the limits?